In short the answer would be to use a good (preferably home-made) stock.
For recommendations of soups on-site; Chicken, French Onion and Tomato Soups all take some beating!
Winton
I think this beggars the question, what have you tried before, and why was it not good tasting?
Angela, we need a bit more information; likes, dislikes, vegetarian/seafood/meat/chicken, creamy/low fat, hot etc. etc.
General rules for basic soups.
Start with something basic like gently brown onions and add to that.
Going for something with veg add them and allow to soften a little, add a few sympathetic spices/herbs and add good stock (homemade or from a decent stockcube/tub/jar etc).
Add other things like chicken/beef/lamb
cook together until nice and soft....
Steve